Travelers such as yourself have a number of water-purification options these days. The SteriPEN (hydro-photon.com) is one of the more innovative ones. It uses ultraviolet light to kill viruses, protozoans, and just about anything else bad in the water. You simply insert the SteriPEN in to the water in question, turn it on, and in a minute or so you have drinkable water. And the cost is not unreasonablea kit that includes a SteriPEN, a pre-filter to clean out particulates, and a plastic bottle, sells for $120. Theyve proven very popular, I think for good reason.
Another electric" purifier (the SteriPEN requires batteries) is the MIOX Purifier from MSR ($140; msrcorp.com). It uses an electrical charge to create a virus-killing salt-based solution. One advantage is that you can treat larger volumes of water in a batch than the SteriPEN. But its not as fast; it can take up to four hours to kill cryptosporidium and 30 minutes for Giardia.
One issue with both is that anything with batteries can go haywire. Or you can find yourself unable to find batteries (the MIOX takes fairly exotic CR123 batteries) or charge them. So another option is to combine a filter with a purifying solution. Katadyns Pocket Filter ($220; katadyn.com) is a tough, reliable choice. And when paired with something such as MSRs SweetWater Purifier Solution, you can clean your water of both organisms such as Giardia, which the filter takes out, and viruses. Or you can get filters such as the MSR Miniworks ($85) or SweetWater Microfilter ($65).